GEN energija Seismic Hazard Analysis Project for Krško 2

GEN energija Seismic Hazard Analysis Project for Krško 2

Presentation to Slovenian Nuclear Safety Administration 27 January 2015

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Project Goals

• Assess capability of faults within 5 km of the proposed East and West site for Krško NPP 2 (JEK 2)

• Determine Design Basis Earthquake (Safe Shutdown Earthquake, SL-2) on basis of PSHA results


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Project Team

• Sponsor – GEN energija

• Team composed of RIZZO Associates (RIZZO) and the Geologic Survey of Slovenia (GeoZS) will execute the project


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Key Guidance

• Slovenian Regulation: Zakon o varstvu pred ionizirajočimi sevanji in jedrski varnosti (ZVISJV)

• Primary Guidance • IAEA Safety Standards, Specific Safety Guide SSG-9

• Other Guidance • USNRC Regulatory Guide 1.208 • SSHAC, NUREG/CR-6372 • USNRC NUREG-2117


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Quality Assurance

• Work will be carried out under the RIZZO Quality, Health, Safety, and Environmental (QHSE) program

• Implements requirements including: • ISO 9001:2008, ISO 14001:2004, ISO/IEC

17025:2005 • US 10 CFR 50, Appendix B; 10 CFR 21 • ASME NQA-1


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Framework for Technical Approach

• SSHAC Process for incorporation of uncertainty • Compile information • Evaluate information • Based on evaluations, develop an integrated

representation of the center, body, and range of technically defensible interpretations

• Peer review • Complete documentation of process


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SSHAC Study Level

• Krško SHA Project will be carried out as a SSHAC Level 2 study • Interactions with resource and proponent

experts carried out individually and often remotely

• Participatory peer review panel (PPRP) will be used

• Usually associated with SSHAC Level 3 and 4 studies


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Framework for Technical Approach


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PHASE 1 FIELD INVESTIGATIONS


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Phase 1-Field Investigations

• Expand upon previous work • Emphasis on Orlica fault zone (OFZ)

and Artiče Structure (AS) • Identify existence and characterize

capable faults within 5 km of the East and West sites

• Support update of seismotectonic model and SSC models


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Phase 1 – Field Investigations

• Integrated and iterative approach • Tectonic geomorphic characterization • Geophysical investigation • Drilling • Paleoseismological investigation • Age dating

• Level of effort will vary depending on what is encountered in these studies


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Tectonic Geomorphic Characterization

• Investigate geomorphology of Krško region to identify evidence of most recent tectonic activity • Lineament analysis • Channel profile analysis • Drainage basin morphology • Basin-averaged denudation


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Geophysical Investigation

• Shallow high-resolution seismic reflection profiles • Target: top of Pontian, Plio-Quaternary, Quaternary

sediments • High number of active channels, high data fold • Seismic source test prior to acquisition of every HRS

profile • Targets:

• Zones with the projected possibility of paleoseismic trenching

• Zones with open questions on fault presence/geometry


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TABLE 2-1 Proposed Geophysical (High Resolution Seismic Reflection) Lines.

[Proposed] Geophysical Lines

Line Length Target Structure Target Depth Range Priority HRS Močnik 2015 2.0 km Artiče structure 20 - 300 m Necessary HRS Sromljica 2015 0.6 km Sromljica fault 20 - 150 m Necessary HRS Gabrnica 2015 0.4 km Gabrnica fault 20 - 150 m Necessary HRS Župelevec 2015 1.3 km Artiče structure 20 - 300 m Necessary HRS Mrtvi potok 2015 2.2 km Orlica fault zone 40 - 500 m Necessary HRS Artiče A 2015 1.5 km Artiče structure 20 - 300 m Optional* HRS Artiče B 2015 1.5 km Artiče structure 20 - 300 m Optional* * Optional: either HRS Artiče A 2015 or B 2015 will be selected, based upon the results of HRS Sromljica 2015


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Drilling

• To support interpretation of high resolution seismic (HRS) data.

• Seismic downhole, fully cored • 2 boreholes necessary*:

* Optional boreholes have also been identified that may be recommended if additional subsurface information is necessary to support the HRS profiles.


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Paleoseismological Investigations

• Up to 8 provisional sites to be identified on the OFZ and AS based on other Phase 1 studies

• 5 of these sites will then be studied with geophysical methods to determine their appropriateness for trenching

• 3* sites will be trenched if appropriate conditions are encountered

* If it is determined that the three trenches are not adequate or if excavation problems arise on one of the trenches, a recommendation will be made for selection from the five locations identified for possible trench excavation.


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Age Dating

• Goal is to obtain Plio-Quaternary geochronology for the 25-km site vicinity

• Targets for sampling will be determined from other field investigations • Deformed and undeformed sediments • Fault materials • Constraints on landscape evolution

• Multiple appropriate techniques


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Age Dating

• Multiple appropriate techniques: • Cosmogenic radionucleides (CRN) • Optically stimulated luminescence (OSL) • Uranium-Thorium (U-Th) • Argon-Argon (40Ar/39Ar) • Radiocarbon (14C)


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Phase 1 Reporting

• For each field investigation technique, a report will be prepared

• Phase 1 Summary Report that integrates the results of the studies

• Fault Capability Report • Provide capability assessment per SSG-9 • Peer Review


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PHASE 2 FAULT CAPABILITY

AND SEISMIC SOURCE CHARACTERIZATION


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• Assess tectonic deformation (fault displacement and surface deformation) within a minimum of 5 km from the proposed JEK 2 sites

• If determined capable assess fault displacement/surface deformation hazard following SSG-9 guidance with respect to the safe operation of the proposed JEK 2

Objectives for Assessing Fault Capability


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Fault Capability

• In accordance with IAEA’s SSG 9 a capable fault is defined as:

•

5 km


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Basis for Assessing Fault Capability

• Compile sufficient data on the behavior and geometry of faults within 5 km of the sites • Phase 1 investigations

• Develop a robust understanding of level of tectonic activity within the region • Updated and defensible seismotectonic model

• Develop a defensible technical basis for a reasonable time period to evaluate fault capability

• Participation of PPRP


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Fault Capability Hazard

• Presence of a capable fault is not necessarily an exclusionary criteria; however, if, based on “reliable evidence” it has the potential to affect the safe operation of the plant, further evaluations may be considered

• A probabilistic fault displacement hazard analysis (PFDHA) may be appropriate • Currently not in scope of work


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Seismic Source Characterization (SSC)

• Objective is to characterize seismic sources for input to the Probabilistic Seismic Hazard Analysis (PSHA) • Consider seismic sources (structures and

zones) within the region that may be significant to the two sites

• Develop seismic source model(s)


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Earthquakes in Regional Area

Period: 567 – 2013 MS ≥ 4.0


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Integration Team

• Establish SSC Technical Integration Team to: • Compile and evaluate available data on neotectonic

activity • Update historical seismicity of the region and identify

seismic sources • Update the existing seismotectonic model based on

new data • Interview proponents of neotectonic models

• Develop SSC model(s) • Inputs and model(s) reviewed by PPRP


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SSC Model(s)

• SSC model(s) consist of: • Earthquake catalogue • Seismotectonic model • Identification of seismic sources • Maximum magnitude distribution • Recurrence models • Rupture characteristics


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SSC Input to PSHA

• Identify and characterize seismic sources based on: • Recurrence • Magnitude frequency distribution • Source geometry (Length, width and depth) • Distance from sites and seismogenic depth • Maximum earthquake


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PHASE 3 GROUND MOTION CHARACTERIZATION,

PROBABILISTIC SEISMIC HAZARD ANALYSIS, AND CONTROL POINT GROUND MOTION


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Ground Motion Characterization


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Ground Motion Characterization

• Determine reference rock condition for PSHA (Shear-wave velocity, depth, attenuation characteristic)

• Model consists of: • Median ground motion and uncertainty • Ground motion variability (“sigma”)

• PPRP review prior to use in PSHA


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Probabilistic Seismic Hazard Analysis

• Use SSC and GMC inputs to develop PSHA results for reference rock condition • Ground motion hazard curves • Uniform hazard response spectra


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Probabilistic Seismic Hazard Analysis

• Deaggregation of results (dominant magnitudes and distances) contributing to hazard

• Sensitivity analyses


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Site Response Analysis

• Assess information from JEK1 and other studies to develop approximate site response

• Use to adjust ground motion for the PSHA reference rock condition to corresponding ground motion for the control point


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Control Point Ground Motion

• Control point at the top of consolidated material beneath the surficial gravels

• Basis for SL-2 ground motion is the uniform hazard response spectrum with a 1E-4 mean annual frequency of exceedance


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Control Point Ground Motion

• Vertical control point response spectrum is determined from the horizontal control point response spectrum using an appropriate vertical-to-horizontal ratio function


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SUMMARY


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Summary

• GEN is implementing an integrated program to address seismological suitability issues and determine SL-2 ground motion response spectra

• Work will be carried out under the RIZZO QHSE program to ensure data are appropriate for nuclear site characterization

Documents

GEN energija Seismic Hazard Analysis Project for Krško 2